1. Field of the Invention
This invention relates to a phosphorus-free based halogen-free flame-retardant resin composition that has high flame-retardant properties that pass foreign flame-retardant standards (EN, DIN, BS), is excellent in mechanical characteristics, and has a flat and smooth extrusion appearance, a phosphorus-free based halogen-free flame-retardant insulated electric wire and a phosphorus-free based halogen-free flame-retardant cable.
2. Description of the Related Art
In recent years, wires and cables with insulations that do not use polyvinyl chloride and halogen based flame-retardants so as to be reduced in environmental load spread rapidly as so-called “eco-electric wire” and “eco-cable”.
In the halogen-free flame-retardant electric wire and the halogen-free flame-retardant cable, it is common to use a resin composition as an insulator of the electric wire, the resin composition configured such that halogen-free flame-retardants such as magnesium hydroxide are blended in a polyolefin in large amounts.
In order to realize high flame-retardant properties in a vertical flame test that pass the foreign flame-retardant standards (EN, DIN, BS) by using the halogen-free flame-retardants such as magnesium hydroxide, it is necessary for the halogen-free flame-retardants to be blended therein in large amounts, thus there is a problem that mechanical characteristics such as tensile strength, elongation are drastically lowered.
For the purpose of solving the above-mentioned problem, a method of using a polyolefin as a base polymer has been proposed, the polyolefin being polymerized by a metallocene catalyst, and having narrow molecular weight distribution, high strength and flexibility (for example, refer to JP-A-2009-019190).